The present invention relates to the general field of gas turbines, and more particularly it relates to a gearbox for driving accessories of a gas turbine.
The field of application of the invention is that of gas turbines for airplane or helicopter engines, and also for auxiliary power units (APUs).
In general, an airplane or helicopter gas turbine engine includes a gearbox for driving a plurality of accessories of the turbine or for driving auxiliary equipment, such as in particular various pumps for producing hydraulic energy, for feeding fuel, for lubrication, electricity generators for producing electrical power, e.g. of the integrated drive generator (IDG) and of the variable frequency generator (VFG) type, etc. Such an accessory gearbox is commonly referred to by the abbreviation AGB.
In known manner, an AGB contains one or more gear trains, each made up of a plurality of gearwheels that are driven in rotation by a power transmission shaft, which shaft is coupled to a shaft of the turbine. Each accessory is generally mounted against one of the lateral faces of the gearbox and includes a drive shaft that couples with one of the gearwheels of the gear train(s). In addition to this accessory support function, these lateral faces also perform a bearing support function, a sealing function, or indeed a lubrication function. While the turbine is in operation, a fraction of the mechanical power it generates is taken from the turbine shaft and is transmitted via the power transmission shaft and the gear trains to the drive shafts of the various accessories mounted on the AGB in order to drive them.
The size of AGBs varies in particular as a function of the number and of the kinds of accessories it is to drive, which accessories also give rise to considerable overhangs.
When designing an AGB, it is therefore important to reduce as much as possible the overall size and weight of the AGB. In application FR 09/50617, this reduction is made possible by acting on the positioning of the accessories relative to one another as a function of their individual sizes. Nevertheless, there still exists a need to further reduce this size and generally to increase the reliability of such an AGB.